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As one of the important blue carbon pools in tropical and subtropical intertidal zones, mangroves are widely distributed along the coast of Guangxi in China. To deeply explore the variations of potential suitable habitats for mangroves in China under the background of climate change, based on remote sensing interpretation data of coastal wetlands in Guangxi, global marine environment and bioclimatic environment data in 2021, we constructed a maximum entropy habitat distribution model to simulate the spatial distribution of potential suitable areas for mangroves and the invasive species, Spartina alterniflora, along the coast of Guangxi, and predicted the patterns under extreme climate change scenarios (SSP5-8.5). The results showed that the interpreted area of mangrove forests along the coastline of Guangxi was 9136.7 hm2 in 2021, while the predicted area of potential suitable habitat area was 55955.9 hm2. Current distribution area of mangroves had basically covered its potential high suitability area and nearly 10% of the moderate suitability area. The current area of S. alterniflora was 1320.4 hm2, and the predicted area of potential high suitability area was twice of current area, indicating that there was still a large proportion of high suitability area that was not occupied by S. alterniflora. The most important environmental factors driving the distribution of potential habitats in mangroves were offshore Euclidean distance (62.2%), terrain deviation index (8.7%), average sea surface temperature in the hottest season (6.1%), and seabed terrain elevation (5.6%). The contribution of geographical conditions on mangrove distribution was predominant. Under the climate change scenario (SSP5-8.5), potential suitable area for mangroves would increase by 5.3%, while that for S. alterniflora would decrease by 3.1%. The overlapping proportion of the potential suitable area for mangroves and S. alterniflora was similar under current and SSP5-8.5 scenarios, being 15.2% and 14.5%, respectively. In the future, it is necessary to strengthen the protection and ecological restoration of mangroves along the coast of Guangxi and there is great challenge for preventing further invasion of S. alterniflora.

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OBJECTIVE: To investigate factors that differentiate elderly adults in rural China who accept free vision screening and cataract surgery from those who could benefit from vision care but refuse it when offered. DESIGN: We conducted a population-based, cross-sectional study between October and December 2016. Logistic regression models were used to examine the predictors of accepting free vision screening and cataract surgery. SETTING: Rural communities in Handan, China. PARTICIPANTS: Adults aged 50 years or older, with presenting visual acuity ≤6/18 in the better seeing eye, suspected by examining ophthalmologist to be due to cataract. RESULTS: Among 613 persons with cataract identified on a population basis, 596 (97.2%) completed the household survey (mean (SD) age, 71.5 (10.0) years; 79.8% female). A total of 214 persons (35.9%) refused participation, while 382 (64.1%) took part in the vision screening. A total of 193 (50.5%) participants were found eligible for surgery, while 189 (49.5%) were not. Among 99 randomly selected participants who were offered immediate free surgery, surgery was accepted by 77 participants (77.8%) and refused by 22 (22.2%). In the multivariate model, being engaged in income-generating activities (p<0.01), self-reported better physical capacity (p<0.001) and having had a recent physical examination (p=0.01) were significantly associated with acceptance of vision screening. The only variable significantly associated with acceptance of surgery was presenting visual acuity, with better vision inversely associated with acceptance of surgery (p<0.05) models. CONCLUSION: Our results suggest that refusal of basic eye examinations may be at least as important a determinant of low surgical rates in rural China as lack of acceptance of surgery itself.

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Bamboo scrimber is widely used in interior decoration, architecture, and many other fields. However, it has caused huge security risks due to its inherent flammability and easy-to-produce toxic volatiles after combustion. In this work, the bamboo scrimber with superior flame retardant and smoke suppression properties was produced via the coupling of phosphocalcium-aluminum hydrotalcite (PCaAl-LDHs) with bamboo bundles. The results demonstrated that the flame-retardant bamboo scrimber (FRBS) heat release rate (HRR) and total heat release (THR) were, respectively, reduced by 34.46% and 15.86% compared with that of untreated bamboo scrimber. At the same time, the unique multi-layer structure of PCaAl-LDHs effectively slowed down the release rate of flue gas by extending its escape path. Cone calorimetry showed that the total smoke emissions (TSR) and specific extinction area (SEA) of FRBS were, respectively, reduced by 65.97% and 85.96% when the concentration of the flame retardant was 2%, which greatly developed the fire safety of the bamboo scrimber. This method not only improves the fire safety of bamboo scrimber but can also be expected to broaden its use scenarios.

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To improve the flame retardancy of bamboo scrimber, flame-retardant CaAl-PO4-LDHs were synthesized via the coprecipitation method using PO43- as the anion of an intercalated calcium-aluminum hydrotalcite in this work. The fine CaAl-PO4-LDHs were characterized via X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), cold field scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and thermogravimetry (TG). Different concentrations (1% and 2%) of CaAl-PO4-LDHs were used as flame retardants for the bamboo scrimber, and the flame retardancy of the bamboo scrimber was characterized via cone calorimetry. The results showed that CaAl-PO4-LDHs with excellent structures were successfully synthesized via the coprecipitation method in 6 h and at 120 °C. Compared with the bamboo scrimber without the flame retardant treatment, the peak heat release rate (HRR) of the bamboo scrimber treated with 1% and 2% concentrations of flame-retardant CaAl-PO4-LDHs decreased by 16.62% and 34.46%, the time taken to reach the exothermic peak was delayed by 103 s and 204 s and the Time to Ignition (TTI) was increased by 30% and 40%, respectively. Furthermore, the residual carbon of the bamboo scrimber did not change significantly, increasing by 0.8% and 2.08%, respectively. CO production decreased by 18.87% and 26.42%, respectively, and CO2 production decreased by 11.11% and 14.46%, respectively. The combined results show that the CaAl-PO4-LDHs synthesized in this work significantly improved the flame retardancy of bamboo scrimber. This work exhibited the great potential of the CaAl-PO4-LDHs, which were successfully synthesized via the coprecipitation method and applied as a flame retardant to improve the fire safety of bamboo scrimber.

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Background: To identify an optimal model for diabetic retinopathy (DR) prediction in Chinese rural population by establishing and comparing different algorithms based on the data from Handan Eye Study (HES). Methods: Five algorithms, including multivariable logistic regression (MLR), classification and regression trees (C&RT), support vector machine (SVM), random forests (RF), and gradient boosting machine (GBM), were used to establish DR prediction models with HES data. The performance of the models was assessed based on the adjusted area under the ROC curve (AUROC), sensitivity, specificity, and accuracy. Results: The data on 4752 subjects were used to build the DR prediction model, and among them, 198 patients were diagnosed with DR. The age of the included subjects ranged from 30 to 85 years old, with an average age of 50.9 years (SD = 3.04). The kappa coefficient of the diagnosis between the two ophthalmologists was 0.857. The MLR model revealed that blood glucose, systolic blood pressure, and body mass index were independently associated with the development of DR. The AUROC obtained by GBM (0.952), RF (0.949), and MLR (0.936) was similar and statistically larger than that of CART (0.682) and SVM (0.765). Conclusions: The MLR model exhibited excellent prediction performance and visible equation and thus was the optimal model for DR prediction. Therefore, the MLR model may have the potential to serve as a complementary screening tool for the early detection of DR, especially in remote and underserved areas.

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Bamboo has been widely used in architecture, decoration and other fields because of its advantages of short growth period, high strength and degradability. However, bamboo, as a combustible material like wood, are easy to burn and cause building fires. However, the existing bamboo water-based flame retardants have some shortcomings, such as strong hygroscopicity and easy loss, which limits the application of bamboo products. In order to improve the flame retardant performance of bamboo, CaAl-SiO2 layered double hydroxide (LDH) as bamboo flame retardant was synthesised by coprecipitation method. The influence of preparation technology on CaAl-SiO3-LDH structures and properties as well as the flame retardant and smoke suppression characteristics of flame retardant-treated bamboo was discussed. The results revealed that the crystallisation temperature, crystallisation time and crystallisation concentration of CaAl-SiO3-LDHs considerably affected its structure and properties. The optimum technological parameters for preparing CaAl-SiO3-LDHs by using the coprecipitation method are as follows: crystallisation temperature of 100 °C, crystallisation time of 9 h and Ca2+ solution molar concentration of 0.33 mol/L. Compared with nonflame-retardant wood, CaAl-SiO3-LDH flame retardant treatment delayed the peak time of the heat release rate by 20 s and the ignition time by 77.78% and increased the carbon residue rate by 9.54%. This study can provide reference for the research of new flame retardant for bamboo products.

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In the present study, the sustained-release system loading citral was synthesised by using PNIPAm nanohydrogel as a carrier and analysed its drug-release kinetics and mechanism. Four release models, namely zero-order, first-order, Higuchi, and Peppas, were employed to fit the experimental data, and the underlying action mechanism was analysed. The optimised system was applied to treat a bamboo mould, followed by assessment of the mould-proof performance. Our experimental results revealed that the release kinetics equation of the system conformed to the first order; the higher the external temperature, the better the match was. In the release process, PNIPAm demonstrated a good protection and sustained-release effect on citral. Under the pressure of 0.5 MPa, immersion time of 120 min, and the system concentration ratio of 1, the optimal drug-loading parameters were obtained using the slow-release system with the best release parameters. Compared to the other conditions, bamboos treated with pressure impregnation demonstrated a better control effect on bamboo mould, while the control effect on Penicillium citrinum, Trichoderma viride, Aspergillus niger, and mixed mould was 100% after 28 days. Moreover, the structure and colour of bamboo remained unchanged during the entire process of mould control.

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Bamboo, a natural material, has been widely used in the fields of decoration, architecture and furniture. However, bamboo is easy to mildew and lose its use value. In this paper, the inhibition mechanism and antibacterial activity of a natural antibacterial agent citral on bamboo mould and its anti-mildew effect on bamboo were studied. The results showed that citral could change the shape of mycelium, destroy the integrity of mycelium structure, cell wall and cell membrane structure, thereby causing leakage of nucleic acids, proteins and other substances in the cell, as well as destroy the pH balance of the inside and outside of the cell, to inhibit or kill mould. When the concentration of citral is 100 mg ml-1, the antibacterial rates of citral against Penicillium citrinum (PC), Trichoderma viride (TV), Aspergillus niger (AN) and a hybrid fungi group comprising PC, TV and AN (Hun) were more than 100%. However, compared with the direct effect of citral on mould, the antibacterial property of bamboo treated with citral was significantly reduced, the mildew proof effect can be achieved only if the concentration of citral to treat bamboo is increased to more than twice the concentration of citral directly acting on mould.

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Bamboo is a widely used renewable and degradable biomass material; however, its sustainable utilisation is hindered by its susceptibility to mold. The current bamboo anti-mold technology is mainly based on organic chemical agents; these agents can easily induce mold resistance in bamboo with long-term use, and can even adversely affect human health. In the present study, the poly(N-isopropyl acrylamide) (PNIPAm)/citral nanohydrogel was prepared by encapsulating the natural antibiotic citral in PNIPAm for the anti-mold treatment of bamboo. The results revealed that this nanohydrogel exhibited a core-shell system with citral as the 'core' and PNIPAm as the 'shell', an average hydrodynamic diameter of 88.1 nm, and a low critical solution temperature (LCST) of 35.4 °C. After the high-pressure impregnation with the nanohydrogel, the bamboo strips showed excellent control effects toward common bamboo molds. Therefore, the nanohydrogel demonstrated high efficiency and it may become an ideal alternative to organic chemical anti-mold agents, thus showcasing its significant potential in the field of mold prevention for bamboo.

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PURPOSE: The aim of this study was to explore the association between diabetic retinopathy (DR) and the risk of 6-year death, as well as the association between visual impairment (VI) and the risk of 6-year death in a rural Chinese population of age ≥30 years. METHODS: This was a population-based cohort study. In 2006-2007, 6,830 subjects aged ≥30 years were recruited from 13 villages in Northern China through clustered randomization. In 2012-2013, a 6-year follow-up was further done. Six different proportional hazards models, with different confounders adjusted, were used to explore the association between baseline DR and risk of death. RESULTS: 5,570 subjects were included in this study by our inclusion and exclusion criteria. Four hundred and ten (7.36%) subjects died by follow-up. The median ages of the dead subjects and survived subjects were 67 (interquartile range [IQR]: 58-72) years and 52 (IQR: 42-58) years (Z = 21.979, p < 0.001). Male accounted for 62.20 and 44.92% among the dead and survived subjects (χ2 = 45.591, p < 0.001). Besides, compared with those survived, the dead were found to be with lower education (χ2 = 109.981, p < 0.001), lower marriage rate (χ2 = 101.341, p < 0.001), lower income (χ2 = 123.763, p < 0.001), higher proportion of smoking (χ2 = 8.869, p = 0.003), higher systolic blood pressure (Z = 10.411, p < 0.001), lower body mass index (Z = -3.302, p = 0.001), larger spherical equivalent error (Z = 4.248, p < 0.001), lower intraocular pressure (Z = -4.912, p < 0.001), smaller anterior chamber depth (Z = -9.186, p < 0.001), larger length thickness (Z = 11.069, p < 0.001), higher fast blood glucose level (Z = 5.650, p < 0.001), higher total cholesterols (Z = 2.015, p = 0.044), higher low-density lipoprotein (Z = 2.024, p = 0.043), and higher proportion of drug usage (χ2 = 56.108, p < 0.001). Besides, the dead subjects were more likely to be with VI, glaucoma, cataract, age-related macular degeneration, diabetes, and DR. Hundred and forty-eight subjects were diagnosed with DR at baseline, and 33 (22.30%) of them were dead before follow-up. By adjusting all relative confounders in a proportional hazards model, DR was found to be a risk factor of 6-year death, the hazard ratio was 1.739 (95% confidence intervals: 1.080, 2.803). Another 5 different statistical models with different confounders adjusted also revealed a statistically significant association between DR and 6-year death. The association between VI and 6-year death was not statistically significant. CONCLUSIONS: DR increased the risk of 6-year death in a rural Chinese population aged ≥30 years, while VI did not.

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PURPOSE: To determine the six-year incidence, risk factors, and causes of visual impairment in a Chinese population. METHODS: This was a population-based study of eye disease in Chinese adults in a rural district of Handan in China. 6,830 individuals were invited to participate in 2006 and 5,394 returned for follow-up in 2012. All participants underwent standardized eye examinations. Visual impairment was defined according to WHO criteria. The incidence of visual impairment was age- and gender-standardized to the 2010 China Census. Multivariable logistic regression analysis was used to determine risk factors for visual impairment. RESULTS: The leading causes of visual impairment were cataract and refractive error. Based on presenting visual acuity (PVA), the six-year incidence rates of low vision and blindness were 5.2% and 0.5%, respectively. Incidence of low vision was associated with older age (p < .001), less education (p < .001), diabetes (p < .05), and lower BMI (p < .001). The incidence of blindness was associated with diabetes (p < .05). Based on best-corrected visual acuity (BCVA), the six-year incidence rates of low vision and blindness were 0.8% and 0.1%, respectively. Incidence of low vision was associated with older age (p < .001) and lower BMI (p < .05). None of these factors were associated with the incidence of blindness. CONCLUSION: In Handan, the incidence of visual impairment was high and associated with older age, less education, diabetes, and lower BMI. The majority of cases were due to unoperated cataract and uncorrected refractive error, reflecting the need for improved eye care in this region.

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The aim of this study was to overcome drawbacks of the inhomogeneous dispersion and facile agglomeration of nano-ZnO/poly(N-isopropylacrylamide) composite hydrogels (nano-ZnO/PNIPAm composite hydrogels) during synthesis and improve the anti-mold property of the nano-ZnO/PNIPAm composite hydrogels. Here, nano-ZnO/PNIPAm composite hydrogels were prepared by the radical polymerization method. Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), differential scanning calorimeter (DSC), and dynamic light scattering (DLS) were used to characterize the effects of different dispersants on the particle sizes, dispersions, and phase transition characteristics of the nano-ZnO/PNIPAm composite hydrogels. The anti-mold properties of nano-ZnO/PNIPAm composite hydrogels were studied. Results revealed that the nano-ZnO/PNIPAm composite hydrogel prepared by the addition of nano-ZnO dispersion liquid exhibited the smallest particle size, the most homogeneous dispersion, and the highest stability. The addition of the dispersant did not change the phase transition characteristics of nano-ZnO/PNIPAm, and the nano-ZnO/PNIPAm composite hydrogels (Pf) exhibited good anti-mold properties to the bamboo mold.

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BACKGROUND: Handan Eye Study (HES), a large population-based cohort study in rural area of northern China, was one of the few studies focusing on the major eye diseases of rural Chinese population. The aim of this study was to introduce the design, methodology and to assess the data quality of the follow-up phase of HES. METHODS: All participants were recruited in Yongnian county of Handan city between 2012 and 2013. Main outcomes were measured by visual quality scales and ocular examinations. We performed the Chi-square test to make comparison of categorical data among groups, One-way analysis of variance and Kruskal-Wallis test was applied to make comparison of continuous data among groups, a post-hoc test was done to make further pairwise comparison. Inter-class correlation coefficients (ICCs) and Kappa coefficients were used to evaluate the consistency between different operators. Logistic regression was used to explore the influence factors of death, odds ratio (OR) and 95% confidence interval (CI) were used to estimate the effect size of each influence factor. RESULTS: The follow-up rate was 85.3%. Subjects were classified into three groups: the follow-up group (n = 5394), the loss to follow-up group (n = 929), and the dead group (n = 507), comparison of their baseline information was done. Compared with the other two groups, age of the dead group (66.52 ±â€Š10.31 years) was the oldest (Z = 651.293, P < 0.001), male proportion was the highest (59.0%) (χ = 42.351, P < 0.001), only 65.9% of the dead finished middle school education (Z = 205.354, P < 0.001). The marriage percentage, body mass index (BMI), best-corrected visual acuity (BCVA), and intra-ocular pressure of the dead group was the lowest either. Spherical equivalent error (SER) of the dead group was the highest. Besides, history of smoking, hypertension, diabetes, and heart disease were more common in the dead group. Multivariate analysis showed that age (OR = 1.901, 95% CI: 1.074-1.108), gender (OR = 0.317, 95% CI: 0.224-0.448), and BCVA (OR = 0.282, 95% CI: 0.158-0.503) were associated with death. While between the follow-up group and the loss to follow-up group, there was only difference on age, gender, BMI, systolic blood pressure and SER. The Cronbach coefficients of all scales used in the follow-up were ≥0.63 and the cumulative variances were ≥0.61, indicating good reliability and validity. The ICCs and Kappa coefficients between different operators were ≥0.69. CONCLUSIONS: HES has a high follow-up rate and a low risk of loss to follow-up bias. Age, gender, and BCVA are influence factors of death. Specifically, male subjects are at a higher risk of death than female, age is a risk factor of death while BCVA is a protective factor for death.

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IMPORTANCE: Provision of refractive changes is important to predict eye care needs for aging population. BACKGROUND: To provide 5-year refractive changes in a rural Chinese adult population. DESIGN: Population-based longitudinal study. PARTICIPANTS: At baseline, 6830 subjects aged 30+ years took part in the Handan Eye Study. A total of 5394 of the 6323 survivors (85.3%) participated in the 5-year follow-up. METHODS: Ocular examinations including standardized refraction were performed according to the same protocol at both baseline and follow-up. MAIN OUTCOME MEASURES: Change in spherical equivalent (SE; sphere + 1/2 cylinder) and astigmatism. RESULTS: A total of 3970 right eyes were available for refraction analysis. The 5-year change in SE for all subjects was +0.17 diopters (D), and was -0.21D, +0.14D, +0.40D and +0.08D for subjects aged 30-39, 40-49, 50-59, and 60-69 years, respectively. By binary regression analysis, myopic shift was associated with severe nuclear opacity, longer axil length, diabetes and large change of lens power, while hyperopic shift was associated with older age and ocular hypertension at baseline. There was a mean change of 0.18D in the against-the-rule astigmatism. CONCLUSIONS AND RELEVANCE: There was a myopic shift for those 30-39 years old and a hyperopic shift from 40 to 69 years old in a rural Chinese adult population. Those with severe nuclear opacity, longer axil length, diabetes and large change of lens power tended to have a myopic shift, while those being older and having ocular hypertension at baseline were prone to have a hyperopic shift. There was also an increase in against-the-rule astigmatism in this population.

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To study the molecular characteristics of Chlamydia trachomatis, the major outer membrane protein gene (ompA) of C. trachomatis from primary school students with trachoma residing in the Qinghai Tibetan area was sequenced and compared with the same serotype in GenBank. In Jianshetang Primary School and Galeng Central Primary School in the Galeng Tibetan Township of Qinghai Haidong Sala Autonomous County, scraped samples were collected from the upper tarsal conjunctiva and lower conjunctival sac of both eyes of 45 students with trachoma, stored at 4°C, and transported to Beijing Tongren Hospital by air within 24 h. The samples were screened for C. trachomatis by real-time PCR. The ompA gene from the C. trachomatis-positive samples was amplified by nested PCR. The serotype was confirmed by National Center for Biotechnology Information (NCBI) BLAST search and homology analysis. The entire ompA gene sequence was compared with the corresponding gene sequences of serotype B strains available in GenBank. Of the 45 students aged 6-13 years with trachoma, 26 C. trachomatis-positive students were identified by the initial real-time PCR screening (average age, (9.09±1.63) years; sex ratio, 1.0), accounting for 57.78% (26/45). The cycle threshold values for real-time PCR were 16.79-37.77. Half (13/26) of C. trachomatis-positive students had a bacterial copy number of >10(5). The compliance rate of the ompA gene sequences with the C. trachomatis serotype B strains in GenBank was up to 99%. Two novel genetic mutations were found when the ompA gene was compared with those of the 11 serotype B strains in GenBank. The two non-synonymous mutations were located at (i) position 271 in the second constant domain, an adenine (A) to guanine (G) substitution (ACT→GCT), changing the amino acid at position 91 from threonine to alanine (Thr→Ala) in all 26 strains; and (ii) position 887 in the fourth variable domain, a cytosine (C) to thymine (T) substitution (GCA→GTA), changing the amino acid at residue 296 from alanine to valine (Ala→Val) in four of the 26 strains. Six mutations were identified relative to ATCC VR-573. The strains could be divided into two gene clusters according to the mutation at nucleotide position 887: CQZ-1 (China Qinghai Tibetan-1) and CQZ-2 (China Qinghai Tibetan-2). We thus detected two novel serotype B mutant strains of C. trachomatis among study subjects with trachoma.

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Infectious conjunctivitis is no longer a common eye disease in cities and developed areas, but in remote mountainous regions of China where living conditions are relatively under-developed, the occurrence of infectious conjunctivitis remains a public health issue. Here, we evaluate the ratio of infectious conjunctivitis among primary school students in the rural areas of Xunhua, Huangyuan, and Huzhu Counties in the Qinghai province of China, and report the microorganisms involved in causing infection. Of the 765 eligible primary school students, 694 participated to this study (a response rateof 90.7%), 381 boys and 313 girls, with a mean age of 7.52 years (range 7-9 years). A clinical diagnosis of infectious conjunctivitis was returned for 238 of the 694 children examined. The ratio of infectious conjunctivitis in Xunhua County (46.64%) was higher compared to that in Huangyuan (26.67%; P=0.03) and Huzhu Counties (23.61%; P=0.02). The leading cause of conjunctivitis was bacterial, followed by chlamydial and viral. Our results show that there is a high ratio of infectious conjunctivitis among rural primary school students in Qinghai province.

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The aim of this study was to investigate the etiological characteristics of Chlamydia trachomatis conjunctivitis among resident students at primary schools in the Qinghai Tibetan area in order to understand the distribution of C. trachomatis and other pathogenic microorganisms, to detect the isolation rate of infectious pathogens, and to provide an evidence for further targeted efforts in the prevent of sporadic trachoma efforts. From two primary schools in Qinghai Province, ocular samples from 35 students who were clinically diagnosed as trachoma cases and 60 normal controls were obtained by swabbing their upper eyelids and lower conjunctival sacs. Samples were preserved at 4°C and airlifted to Beijing Tongren Hospital within 24 h. Real- time polymerase chain reaction (RT-PCR) was used to screen for C. trachomatis, and nested PCR was used to amplify a fragment of the ompA gene for serotype confirmation. Bacterial cultivation and sensitivity tests were conducted based on the 2015 version of the Clinical and Laboratory Standards Institute. Adenovirus, herpes simplex virus, cytomegalovirus, and Epstein-Barr virus were screened by RT-PCR. Among the 35 students with trachoma, 8 came from the Jianshetang Primary School and 27 came from the Central Primary School. Two novel C. trachomatis B serotypes (GenBank accession numbers KU737520 and KU737521) were detected based on a sequence analysis of the ompA gene. Single C. trachomatis infections accounted for 42.86% (9/21) of the cases, and infections with multiple bacteria, particularly Haemophilus influenzae, Staphylococcus aureus, Moraxella catarrhalis, and Streptococcus pneumoniae, accounted for the remaining 57.14% (12/21). Of the 14 C. trachomatis-negative samples, one was positive for adenoviral infection (serotype D) and 13 were positive for bacterial infections (H. influenzae, M. catarrhalis, S. pneumoniae, S. aureus, streptococci other than S. pneumoniae, Staphylococcus epidermidis, Corynebacterium, and Arthrobacterium). In addition to C. trachomatis, the other bacteria and virus that were detected in the boarding students of primary schools in the Qinghai Tibetan area should be emphasized in trachoma prevention and control.

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OBJECTIVE: To understand the distribution of visual impairment caused by trachoma in China and provide evidences for evaluation of eliminating blinding trachoma in China in the mission of Vision 2020. METHODS: Sampling study. The results from the first year 1987 and second (year 2006) national sampling surveys of disabled persons were analyzed. Chi-square test was performed using SAS 9.30 to analyze the rates of visual impairment caused by trachoma in different groups. Unifactor and multifactor analyses were applied to analyze the relevance between visual impairment caused by trachoma and risk factors, including gender and age. RESULTS: The rate of visual impairment caused by trachoma was 102.01 persons/100 000 in 1987 and 17.62 persons/100 000 in 2006. The percentage of trachoma in all kinds of visual impairment was 14.25% in 1987 and 1.87% in 2006, and the difference was significant (F = 1 382.6, P < 0.01). Spatial aggregation was obvious in visual impairment caused by trachoma. H-aggregation areas included Hubei, Sichuan, Anhui, Shannxi, Guizhou, Hunan provinces and Chongqing Municipality. Survival time without trachoma between 1987 and 2006 was significantly different (F = 2 745.9, P < 0.01). The rate and risk of visual impairment caused by trachoma increased with age. Except the group of > 85 years, the rate of visual impairment caused by trachoma in all age groups in 1987 was significantly higher than that in 2006. The risk of visual impairment caused by trachoma in 1987 was 5.8 times that in 2006. If the other risk factors were not involved, the risk in 1987 was 8.75 times that in 2006. The risk in females was twice that in males. CONCLUSION: Both, the rate and risk of visual impairment caused by trachoma were significantly reduced in China. Impressive progresses were achieved in trachoma prevention and control.

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